Benefit of Higher Maximum Force Output in Bone Anchored Hearing Systems: A Crossover Study.

OBJECTIVE To investigate how higher maximum force output (MFO) in bone anchored hearing systems (BAHS) affects perceived benefit and the subjective experience of sound as well as hearing outcomes in subjects with mixed hearing loss. STUDY DESIGN Prospective single-center, randomized crossover design (A-B-A) with within-subject control design. PATIENTS The study included 19 experienced BAHS users with mixed hearing loss in the fitting range of a standard BAHS. INTERVENTIONS The study evaluated two sound processors with differing MFOs and sizes-Device A: standard sound processor with a lower MFO and Device B: superpower sound processor with a higher MFO. OUTCOME MEASURES Speech recognition in noise at different signal to noise ratios, aided thresholds, and questionnaires. RESULTS Speech recognition test showed significant improvements using Device B compared with Device A at both 78 dB SPL (mean difference: 9%) and 75 dB SPL (mean difference: 12%) (p < 0.05). Moreover, speech, spatial and qualities of hearing scale (SSQ12-C) showed a significantly greater perceived benefit with Device B concerning spatial abilities (mean: 0.5-0.6) (p < 0.05). At the conclusion of the study, 58% of participants chose to keep Device A for further use. The main reasons for this were the size of the sound processor and a more comfortable sound experience. CONCLUSIONS A BAHS sound processor with a higher MFO leads to improved speech-in-noise performance in loud/noisy listening situations and is perceived as significantly better to process spatial information in daily listening situations. However, the relation between cosmetics and performance is not straightforward, and several factors seem to affect the selection process of BAHS.